Rotating electric machine

ABSTRACT

A rotating electric machine includes a non-rotating member, a stator fixed to the non-rotating member, a field coil fixed to the non-rotating member, disposed on an inner diameter side of the stator, and having an iron core and a winding wound around the iron core, and a rotor rotatably disposed between the stator and the field coil. The rotor has, at a portion facing the stator, different radial dimensions with respect to a rotary shaft of the rotor between a one end of the rotor in an extending direction of the rotary shaft and a portion different from the one end in the extending direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No.2019-090810, filed May 13, 2019.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a rotating electric machine.

Description of the Related Art

Conventionally, a rotating electric machine including a shaft, a rotorprovided with a magnetic pole that rotates integrally with the shaft, astator oppositely disposed on the outside of the rotor, a bracketrotatably supporting the shaft and accommodating the rotor and thestator, a yoke part fixed to the bracket, having an inner peripheralsurface that faces the rotor via a gap, and forming a magnetic circuittogether with the rotor and the stator, a bobbin engaging with an outerperipheral surface of a thin portion having an outer diameter smallerthan the other portions of the yoke part, a field coil wound around thebobbin to generate magnetic flux, and a holding member joined to thethin portion to hold the bobbin in an axial direction is publicly known(for example, see Patent Document 1).

PRIOR ART DOCUMENT Patent Document

[Patent Document 1] Japanese Patent Application Laid-Open No.2012-244806

SUMMARY OF INVENTION Technical Problem

In the conventional rotating electric machine, no consideration is givento a configuration of efficiently flowing a magnetic flux from a rotorto a stator.

An object of the present invention is to provide a rotating electricmachine capable of efficiently flowing a magnetic flux from a rotor to astator to improve torque.

The present invention is configured as follows as a unit for solving theabove-mentioned problem. According to an aspect of the presentinvention, a rotating electric machine comprises a non-rotating member,a stator fixed to the non-rotating member, a field coil fixed to thenon-rotating member, disposed on an inner diameter side of the stator,and having an iron core and a winding wound around the iron core, and arotor rotatably disposed between the stator and the field coil, whereinthe rotor has, at a portion facing the stator, different radialdimensions with respect to a rotary shaft of the rotor between a one endof the rotor in an extending direction of the rotary shaft and a portiondifferent from the one end in the extending direction.

According to the rotating electric machine of the above aspect, theradial dimensions at portions of the rotor facing the stator aredifferent between a one end of the rotor in an extending direction ofthe rotary shaft and a portion different from the one end of the rotorin the extending direction of the rotary shaft. With such aconfiguration, a magnetic flux can be efficiently made to flow from therotor to the stator, and the torque of the rotating electric machine canbe improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cutaway perspective view of a rotating electricmachine according to the present embodiment.

FIG. 2 is a partially cutaway perspective view showing a housing of FIG.1.

FIG. 3 is a partially cutaway perspective view showing an iron core of afield coil of FIG. 1.

FIG. 4 is a partially cutaway perspective view showing a rotor of FIG.1.

FIG. 5 is a partially cutaway perspective view of a rotating electricmachine according to another embodiment.

FIG. 6 is a partially cutaway perspective view of a rotating electricmachine according to another embodiment.

FIG. 7 is a partially cutaway perspective view of a rotor according toanother embodiment.

FIG. 8 is a partially cutaway perspective view of a rotor according toanother embodiment.

FIG. 9 is a partially cutaway perspective view of a rotor according toanother embodiment.

FIG. 10 is a partially cutaway perspective view of a rotor and an ironcore of a field coil according to another embodiment.

FIG. 11 is a partially cutaway perspective view of an iron core of afield coil according to another embodiment.

FIG. 12 is a schematic diagram of a rotating electric machine accordingto another embodiment.

DESCRIPTION OF EMBODIMENT

Hereinafter, embodiments according to the present invention will bedescribed with reference to attached drawings. It should be noted thatthe following description is merely exemplary in nature and is notintended to limit the present invention, its application, or its use.

A rotating electric machine of an aspect of the present invention isapplicable to HEVs (hybrid electric vehicles), EVs (electric vehicles),and other devices that include an electric motor as a component. In thepresent embodiment, a rotating electric machine for an electric vehicle(EV) will be described as an example.

FIG. 1 is a partially cutaway perspective view of the rotating electricmachine according to the present embodiment. The rotating electricmachine includes a housing 1 that is an example of a non-rotatingmember, a jacket 2 that covers an outer peripheral surface of thehousing 1, and a stator 3, a iron core 4 of a field coil and a rotor 5that are provided in the housing 1. The rotating electric machine isconfigured that the rotor 5 rotates around the iron core 4 with respectto the housing 1, the stator 3 and the iron core 4.

As shown in FIG. 2, the housing 1 includes a bottomed cylindricalhousing body 6 and a lid (not shown) that covers an opening on one endside of the housing body 6. A stepped recessed portion 8 is formed in acenter of a wall portion 7 on the other end side of the housing body 6.A through hole 9 is formed at a center of the stepped recessed portion8. On an inner surface side of the wall portion 7, a guide portion 10 isformed by the stepped recessed portion 8. The guide portion 10 has astepped shape and includes a first convex portion 10 a, a second convexportion 10 b, and a third convex portion 10 c from a tip side thereof.On an outer end surface of the wall portion 7, an inner diameter sideannular rib 11 a around the stepped recessed portion 8, an outerdiameter side annular rib 11 b of an outer periphery, and a plurality oflinear ribs 11 c extending radially and connecting the inner diameterside annular rib 11 a and the outer diameter side annular rib 11 b areformed. Further, an annular groove 12 is formed on an outer peripheralsurface of the housing body 6 over the whole circumference.

The jacket 2 is formed in a cylindrical shape that covers the outerperipheral surface of the housing 1 as shown in FIG. 1. The jacket 2covers the annular groove 12 of the housing 1 and defines a coolingwater passage 13 for flowing cooling water as an example of a heatexchange medium. A plurality of communication holes (not shown)communicating with the cooling water passage 13 are formed in the jacket2, and allows the cooling water to flow through the cooling waterpassage 13 via these communication holes.

The stator 3 includes a stator core 14 and a coil 15. The stator core 14is obtained by laminating a plurality of electromagnetic steel plates.The stator core 14 is attached to the housing 1 such that a laminationdirection of the electromagnetic steel plates coincides with an axialdirection of the iron core 4. The coil 15 is wound around the statorcore 14 to protrude from both ends in the axial direction.

The iron core 4 of the field coil includes a field coil core body 16, afield coil core flange portion 17, and a field coil 18, as shown in FIG.3. The field coil core body 16 includes an iron core portion 19 and aflange portion 20. A circular positioning recessed portion 21 is formedat a center of the end face of the flange portion 20. A flow hole 22 isformed at a center of the positioning recessed portion 21. The flow hole22 extends beyond the central position in a longitudinal direction ofthe iron core portion 19 and reaches near a tip of the iron core portion19. An annular convex portion 23 is formed on an outer peripheral sideof the end face of the flange portion 20. The field coil core flangeportion 17 is fixed to the tip of the iron core portion 19. The fieldcoil 18 is wound around a coil winding portion formed between the fieldcoil 18 and the flange portion 20.

The field coil core flange portion 17 of the iron core 4 is fixed to theguide portion 10 of the housing 1. The first convex portion 10 a of theguide portion 10 is fitted into the positioning recessed portion 21 ofthe field coil core flange portion 17, and the second convex portion 10b of the guide portion 10 is fitted into the annular convex portion 23.Thus, the iron core 4 is supported by the housing 1 in a so-calledcantilever state. In this state, the through hole 9 of the housing 1 andthe flow hole 22 of the iron core 4 communicate with each other. A pipe24 having an outer diameter smaller than the flow hole 22 is insertedinto the flow hole 22 through the through hole 9. Thereby, when coolingwater is supplied into the flow hole 22 through a center hole of thepipe 24 (first flow path), the cooling water reaches a bottom of theflow hole 22 through the center hole of the pipe 24, flows through anannular passage 25 (second flow path) formed between the flow hole 22and the pipe 24 to a through hole 9 side, and then is discharged to theoutside of the flow hole 22. The annular convex portion 23 and thesecond convex portion 10 b are fitted to form an annularly connectedgroove on the outer peripheral portion of the second convex portion 10b. A bearing 26 is disposed in this groove.

As shown in FIG. 4, the rotor 5 includes a first rotor portion 27 and asecond rotor portion 28, and is rotatably supported on an outerperipheral side of the iron core 4 with respect to the stator 3 and theiron core 4.

The first rotor portion 27 includes a first annular portion 29 having acylindrical portion 30 which has a smaller diameter than the firstannular portion 29 and protrudes from the first annular portion 29. Theguide portion 10 of the housing 1 rotatably supports the first annularportion 29 via a bearing 26. Further, a plurality of first extendingportions 31 protrude from the first annular portion 29 to an oppositeside of the cylindrical portion 30. The first extending portions 31 areformed at a predetermined pitch in a circumferential direction of thefirst annular portion 29, and a portion between two adjacent firstextending portions 31 serves as a first relief portion 32. The firstrotor portion 27 is made of a magnetic material, and becomes an S pole,for example, when current is supplied to the winding of the field coil18.

The second rotor portion 28 includes a second annular portion 33. Thesecond annular portion 33 is rotatably supported with respect to thestator 3 and the field coil 18. A pedestal portion 34 having a smallerdiameter than the second annular portion 33 protrudes from the secondannular portion 33. A rotary shaft 35 protrudes from a center of thepedestal portion 34. The rotational force of the rotary shaft 35 istransmitted to a driven part (not shown). Further, a plurality of secondextending portions 36 protrude from the second annular portion 33 to anopposite side to the pedestal portion 34. The second extending portions36 are formed at a predetermined pitch in a circumferential direction ofthe second annular portion 33, and a portion between two adjacent secondextending portions 36 serves as a second relief portion 37. The secondrotor portion 28 is made of a magnetic material, and becomes an N pole,for example, when current is supplied to the winding of the field coil18.

The first rotor portion 27 and the second rotor portion 28 are connectedto each other by positioning pins 38 which are electrically insulated ina state where the first extending portion 31 of the first rotor portion27 and the second extending portion 36 of the second rotor portion 28are positioned at the second relief portion 37 of the second rotorportion 28 and the first relief portion 32 of the first rotor portion27, respectively. Thereby, the first rotor portion 27 and the secondrotor portion 28 are prevented from displacing in a circumferentialdirection and an axial direction of the rotor 5. The first extendingportion 31 and the second extending portion 36 form a cylindricalportion 39.

In the rotating electric machine having the above-describedconfiguration, the driven part drives via the rotary shaft 35 bysupplying current to the coil 15 from an inverter (not shown) and byelectrically rotating the rotor 5. At this time, the coil 15 itselfgenerates heat by supplying current to the coil 15. Therefore, coolingwater is supplied to a cooling water passage 13 formed by the housing 1and the jacket 2. The supplied cooling water flows through the coolingwater passage 13 and absorbs internal heat from the outer peripheralsurface of the housing 1. Further, cooling water is supplied to the flowhole 22 of the iron core 4 via the pipe 24. The supplied cooling waterflows through the annular passage 25 formed between the flow hole 22 andthe pipe 24 to absorb the heat of the field coil 18 via the iron core 4.

As described above, according to the rotating electric machine of theembodiment, the cooling water is supplied not only to the cooling waterpassage 13 between the housing 1 and the jacket 2 but also to an insideof the iron core 4, thereby enabling cooling also from the inside.Therefore, despite the configuration in which the iron core 4 having thefield coil 18 is disposed on an inner diameter side of the rotor 5, theheat generated from the field coil 18 is effectively removed, and a gooddriving state can be secured.

Note that the present invention is not limited to the configurationdescribed in the above embodiment, and various modifications arepossible.

In the above embodiment, the cooling system is a water cooling system,but a cooling system using another heat exchange medium such as an oilcooling system may be used.

In the above embodiment, the cylindrical portion 39 of the rotor 5 isformed in a cylindrical shape having a substantially uniform thickness.However, a part of the cylindrical portion 39 may be thinned orthickened.

In FIG. 5, groove portions 40 (only the groove portion 40 of a firstannular portion 29 side is shown) extending the whole circumference in acircumferential direction with respect to a rotary shaft of the rotor 5are respectively formed on a surface of each rotor portion 27 facing thestator 3 (that is, the outer peripheral surface of the first rotorportion 27 and the outer peripheral surface of the second rotor portion28). Each groove portion 40 has, for example, a substantiallyrectangular cross section and a substantially constant width and depth.The groove portion 40 of the first rotor portion 27 is provided at oneend of the first extending portion 31 that is farther from the secondannular portion 33 of the second rotor portion 28 in an extendingdirection of the rotary shaft of the rotor 5. The groove portion 40 ofthe second rotor portion 28 is provided at one end of the secondextending portion 36 that is farther from the first annular portion 29of the first rotor portion 27. Due to the groove portion 40, a radialdimension of the rotor 5 with respect to the rotary shaft at one end ofthe rotor 5 at a portion facing the stator 3 in the extending directionof the rotary shaft, and the radial dimension at a portion (for example,the center) different from one end of the rotor 5 at a portion facingthe stator 3 in the extending direction of the rotary shaft aredifferent. With such a configuration, A magnetic flux can beconcentrated on a portion from the center of the stator 3 toward therotor 5 as compared with a rotating electric machine having no grooveportion 40. As a result, a magnetic flux can be efficiently made to flowfrom the rotor 5 to the stator 3 to stabilize the rotating state of therotor 5 and improve the torque of the rotating electric machine.

In FIG. 6, inner surfaces of the first extending portion 31 of the firstrotor portion 27 and the second extending portion 36 of the second rotorportion 28 are configured by curved surfaces 35 a that gradually changein thickness toward the outer diameter toward a tip of the rotor 5. Inother words, each of the rotor portions 27 and 28 of the rotor 5 has, ata portion facing the stator 3, an inclined surface 51 that faces theiron core 4 and inclined to separate from the iron core 4 as goingtoward a center from one end in the extending direction of the rotaryshaft of the rotor 5. Each inclined surface 51 is disposed to face theiron core 4 in each of the first extending portion 31 of the first rotorportion 27 and the second extending portion 36 of the second rotorportion 28. Each inclined surface 51 is curved in a radial directionwith respect to the rotary shaft of the rotor 5 and in a direction awayfrom the iron core 4. That is, a thickness of the first extendingportion 31 and the second extending portion 36 is thicker on the baseportion side, and is gradually thinner toward the tip. Due to theinclined surface 51, the radial dimension of the rotor 5 with respect tothe rotary shaft at one end of the rotor 5 at a portion facing thestator 3 in the extending direction of the rotary shaft, and the radialdimension at a portion (for example, the center) different from one endof the rotor 5 at a portion facing the stator 3 in the extendingdirection of the rotary shaft are different. With this configuration, itis possible to obtain a substantially uniform magnetic flux distributionat a portion of the second extending portion 36 facing the stator 3 ascompared with a rotating electric machine that does not have theinclined surface 51. As a result, a magnetic flux can be efficientlymade to flow from the rotor 5 to the stator 3, and the torque of therotating electric machine can be improved.

In this case, the field coil 18 wound around the iron core portion 19 ofthe iron core 4 preferably has a radial outer edge extending along theinclined surface 51 of the rotor 5. In FIG. 6, the field coil 18 has,for example, a stepped shape, that is, a step-like shape in which aradial outer edge approaches the iron core 4 in a radial direction ofthe field coil 18 as going from the center to both ends in the extendingdirection of the rotary shaft of the rotor 5. In FIG. 6, the field coil18 has a rugby ball shape, an elliptical shape, or a spindle shape as awhole along the inner surface shape of the first extending portion 31and the second extending portion 36 so that the field coil 18 is woundto form a plurality of steps. Thus, an effective cross-sectional area ofthe field coil 18 can be increased by effectively utilizing a spaceinside the rotor 5. Further, since the number of turns of the field coil18 can be increased, a winding length of the field coil 18 in theextending direction of the rotary shaft of the rotor 5 can be reduced ascompared with the rotating electric machine of FIG. 1. As a result, theiron core 4 is shortened in the extending direction of the rotary shaftof the rotor 5, and the rotating electric machine can be downsized inthe extending direction of the rotary shaft of the rotor 5. Note thatthe same effect can be obtained even when the outer edge of the fieldcoil 18 is not step-like shaped but linear or curved.

In the above embodiment, a flow path constituted by the pipe 24 and theannular passage 25 is provided, but this flow path can be omitted. Thatis, the present invention can be applied also to a rotating electricmachine having no flow path.

Further, for example, as shown in FIG. 12, the present invention can beapplied to a rotating electric machine in which field coils 18 areprovided at both ends of the stator 3 in the extending direction of therotary shaft of the rotor 5. In FIG. 12, the rotary shaft of the rotor 5is indicated by a dashed line.

In the above-described embodiment, the first rotor portion 27 and thesecond rotor portion 28 are connected by the positioning pins 38.However, the following configuration may be adopted.

In FIG. 7, a first intermediate member 41 made of a non-magneticmaterial is disposed between the first rotor portion 27 and the secondrotor portion 28. Specifically, the first intermediate member 41 isdisposed to fill a circumferential gap between the first extendingportion 31 and the second extending portion 36. Grooves 36 a are formedin the first extending portion 31 and the second extending portion 36 ata center of a thickness direction thereof from a tip toward a base (thegroove 36 a of a first extending portion 31 side is not shown). On bothside surfaces of the first intermediate member 41, ridges 41 a extendingin a longitudinal direction of the first intermediate member 41 at acenter of a thickness direction thereof and fitted into the grooves areformed, respectively. The groove 36 a and the ridge 41 a may berectangular in cross section. However, if the groove 36 a and the ridge41 a are configured to be slid and engaged from an end face side byforming a T-shaped cross section, it is preferable that displacement inthe radial direction can be reliably prevented.

In FIG. 8, the first intermediate member 41 made of a permanent magnetis disposed between the first rotor portion 27 and the second rotorportion 28.

In FIG. 9, between the tip of the first extending portion 31 and thesecond relief portion 37, and between the tip of the second extendingportion 36 and the first relief portion 32, a second intermediate member42 made of a permanent magnet is disposed. The second intermediatemember 42 may be made of a non-magnetic material as in the case of thefirst intermediate member 41. Also in this case, similarly to the firstintermediate member 41, a groove is formed in the first rotor portion 27and the second rotor portion 28, while a ridge may be formed in thesecond intermediate member 42, and both may be fitted. Accordingly, thefirst intermediate member 41 prevents the displacement of the rotor 5 inthe circumferential direction, and the second intermediate member 42prevents the displacement of the rotor 5 in the axial direction.

In FIG. 10, a reinforcing ring 43 is disposed on an inner diameter sideof the rotor 5. The reinforcing ring 43 has a hollow cylindrical shape,and is formed with a plurality of slits 44 extending in a longitudinaldirection of the reinforcing ring 43 from opening edges of both ends.The slits 44 are formed at a position corresponding to each firstextending portion 31 of the first rotor portion 27 on one end side ofthe reinforcing ring 43, and formed at a position corresponding to eachsecond extending portion 36 of the second rotor portion 28 on the otherend side. A ridge 36 b having a T-shaped cross section that engages witheach slit 44 is formed in each first extending portion 31 and eachsecond extending portion 36 (the ridge 36 b of a first extending portion31 side is not shown). According to the configuration of FIG. 10, it ispossible to position the first rotor portion 27 and the second rotorportion 28 while improving the rotation strength of the rotor 5 withoutthe first intermediate member 41 and the second intermediate member 42as shown in FIG. 9.

In the above-described embodiment, the flow hole 22 is formed at thecenter of the iron core portion 19 of the iron core 4. However, the flowhole 22 may be configured as follows.

In FIG. 11, a plurality of flow holes 45 are formed on the samecircumference on the outer peripheral side of the iron core portion 19.Each flow hole 45 penetrates the iron core portion 19 in the extendingdirection and is opened at both ends of the iron core portion 19. Thefield coil core flange portion 17 is formed with a groove 46 throughwhich the plurality of flow holes 45 communicate. With thisconfiguration, a heat exchange medium, which has flowed in one of theflow holes 45 from one end of the iron core portion 19, flows to theother end, and then flows through the groove 46 to flow to one endthrough any of the remaining other flow holes 45. According to this,cooling can be performed on the outer peripheral side of the iron coreportion 19, and the cooling effect can be further exhibited as comparedwith the case where the flow hole is provided at the central portion.

The present invention is applicable to, for example, HEVs (hybridelectric vehicles), EVs (electric vehicles), and other devices thatinclude an electric motor as a component.

REFERENCE SINGS LIST

-   -   1: housing    -   2: jacket    -   3: stator    -   4: field coil iron core    -   5: rotor    -   6: housing body    -   7: wall portion    -   8: stepped recessed portion    -   9: through hole    -   10: guide portion    -   11: rib    -   12: annular groove    -   13: cooling water passage    -   14: stator core    -   15: coil    -   16: field coil core body    -   17: field coil core flange portion    -   18: field coil    -   19: iron core portion    -   20: flange portion    -   21: positioning recessed portion    -   22: flow hole    -   23: annular convex portion    -   24: pipe (flow path)    -   25: annular passage (flow path)    -   26: bearing    -   27: first rotor portion    -   28: second rotor portion    -   29: first annular portion    -   30: cylindrical portion    -   31: first extending portion    -   32: first relief portion    -   33: second annular portion    -   34: pedestal portion    -   35: rotary shaft    -   36: second extending portion    -   37: second relief portion    -   38: positioning pin    -   39: cylindrical portion    -   40: groove portion    -   41: first intermediate member    -   42: second intermediate member    -   43: reinforcing ring    -   44: slit    -   45: flow hole    -   46: groove    -   51: inclined surface

The invention claimed is:
 1. A rotating electric machine, comprising: anon-rotating member; a stator fixed to the non-rotating member; a fieldcoil fixed to the non-rotating member, disposed on an inner diameterside of the stator, and having an iron core and a winding wound aroundthe iron core; and a rotor rotatably disposed between the stator and thefield coil, wherein the rotor has, at a portion facing the stator,different radial dimensions with respect to a rotary shaft of the rotorbetween a one end of the rotor in an extending direction of the rotaryshaft and a portion different from the one end in the extendingdirection.
 2. The rotating electric machine according to claim 1,wherein the rotor has, at the portion, a groove portion provided at theone end in the extending direction and on a surface facing the stator,and due to the groove portion, the radial dimension of the portion atthe one end in the extending direction and the radial dimension of theportion at a portion different from the one end in the extendingdirection are different.
 3. The rotating electric machine according toclaim 1, wherein the rotor has, at the portion, an inclined surfacefacing the iron core, and inclined so as to separate from the iron coreas going toward a center in the extending direction from the one end inthe extending direction, and due to the inclined surface, the radialdimension of the portion at the one end in the extending direction andthe radial dimension of the portion at a portion different from the oneend in the extending direction are different.
 4. The rotating electricmachine according to claim 3, wherein the field coil has an outer edgein the radial direction extending along the inclined surface of therotor.